The color band code for MELF zener diodes is not standardized, but it looks like Z2 has the same band so if it is ok then you can apply a current-limited variable voltage across it to determine the breakdown voltage. Basically, insert a 10k resistor in series with the positive terminal of an external power supply (ideally a variable one) and measure the voltage across Z2 when this current-limited voltage is applied. If you connect positive to cathode then the voltage will clamp at the zener voltage (+/- a few %); if you connect it positive to anode then it will clamp at 0.6-0.7V.
(mini rant: this is also an excellent object lesson in why you should never use MELF package parts!)